The judge — who found that the Riverside boy, then 10, had the mental capacity to know killing his father was wrong — faces a vexing question: What to do with him?

A Riverside County judge on Monday found a 12-year-old boy responsible for murdering his neo-Nazi father, taking a swipe at both the family and social workers for failing to protect the troubled youngster before he felt compelled to reach for a gun.

"There were so many warning signs,'' Superior Court Judge Jean P. Leonard said from the bench.

But the judge said the evidence showed that the Riverside boy, who was 10 years old when he pulled the trigger, possessed the mental capacity to know that killing his father was wrong. He plotted the murder and then tried to conceal his guilt by stashing the .357 magnum revolver under his mattress, Leonard noted.

Leonard found the boy guilty of second-degree murder and of using a gun while committing a felony.

The youngster's father, Jeffrey Hall, was a West Coast leader for the neo-Nazi organization known as the National Socialist Movement. The judge said Hall's attempts to indoctrinate his son into the hate group corrupted the thought process of a boy who already was disturbed and displaying violent tendencies.

"It's clear that this minor knows more than the average child about guns, hate and violence,'' Leonard said. "This is not a naive little boy unaware of the ways of the world.''

The judge now faces the vexing question of what to do with the boy. Because he was charged as a juvenile, he can be held in state custody only until he is 23. The Times is withholding the boy's identity because of his age.

Most juvenile murderers are sent to one of three juvenile detention facilities run by the state Department of Corrections and Rehabilitation. The institutions house California's most violent juvenile offenders. None currently has an inmate under 14 years old.

The boy's attorney, public defender Matthew Hardy, said it would be a "tragedy" if his client is sent to one of the state facilities.

"That's not a place for children. He'll be spending his time learning how to become a gangbanger or a killer,'' Hardy said.

Leonard indicated she may be open to alternatives, including placing the boy at a facility in Indio run by the Riverside County Department of Probation. The youngster's sentencing hearing, known as a "disposition" in juvenile court, is scheduled for Feb. 15.

As the judge read her decision Monday morning, the boy sat quietly next to his attorney, showing little emotion. Dressed in a gray button-down shirt and peering though plastic-rimmed eyeglasses, the boy wrote on a yellow pad as the verdict was revealed.

Chief Deputy Dist. Atty. Michael Soccio said that emotionally, it was a very difficult case to prosecute, given the age of the boy and the abuse and neglect he had sustained most of his life. Soccio met with him afterward, expressing a hope that he would receive the care he desperately needs.

Still, Soccio said, he was relieved that the boy is to remain in custody.

"Right now in court he was docile, and he can be very sweet," Soccio told reporters after the hearing. "But he's also very dangerous.''

The boy's attorney said during the trial that Hall, when drunk or high, routinely beat his son. Shortly before he was killed, Hall also threatened to leave the family and to set the house on fire with his children and second wife inside.

The boy probably thought he was protecting his family when he fired that revolver, Hardy said.

"He didn't think it was wrong; he thought it was justified," Hardy said after Monday's hearing. "He thought he had to do it."

Hardy plans to appeal Monday's ruling, saying he believes Leonard erred when she found that the boy had the mental capacity to know shooting his father was wrong. Hardy said the boy made conflicting statements to police after the shooting, at one point saying he believed his father would "wake up" and rejoin the family.

"When we create a monster in this society, and I'm not saying [the boy] is a monster, but when we create a monster, we have some responsibility for what that monster does,'' Hardy said.

County social workers visited the Hall family's home more than 20 times, Hardy said, and at the time of the shooting, the boy was a dependent of the court, a designation intended in part to shield him from further abuse.

In the early morning hours of May 1, 2011, the youngster crept downstairs with the loaded revolver, pulled the hammer back and shot his father point-blank in his head as the man slept on the family's living room couch.

The first signs of the boy's penchant for violence surfaced at an early age. When he was a toddler, his grandmother refused to baby-sit him because of his outbursts, and he later was expelled from eight schools for violent behavior, including an attempt to strangle a teacher with a phone cord, according to evidence presented at the trial.

Anna Salter, a clinical psychologist from Wisconsin who appeared for the prosecution, testified that the boy's mental function and grasp of reality probably was warped while he was in the womb, when his mother used heroin, LSD and methamphetamine. The boy's parents divorced shortly after he was born and Hall was awarded full custody of his son when the boy was 3.

The boy's grasp of the world was corrupted even more after his father, an unemployed plumber, joined the neo-Nazi movement in 2009, bringing him along on at least one outing with a hooded member of the Ku Klux Klan and letting him tag along with "patrols" along the Mexican border to search for illegal immigrants, Leonard said.

"He was abused and he was neglected from the womb forward, and this had to affect his thought process,'' the judge said Monday.